Minimally invasive intravascular procedures such as balloon angioplasty and stent placement are important vascular disease treatments for opening vessel blockages of atherosclerotic plaque and thrombi, thereby improving blood flow. A variety of methodologies have been developed for treating vascular blockages, which may involve mechanically removing or reducing the size of the occlusions during thrombectomy, atherectomy, balloon angioplasty, or stenting procedures.
Distal embolization of particulate matter can complicate treatment when embolic particles dislodge while occlusive material is being dilated or cut, and then move downstream from the constricted area to incur a blockage elsewhere and potentially trigger a myocardial infarction, ischema or other complication.
Various interventional systems and methods have been proposed and developed to prevent dislodged embolic material from entering the blood stream and to facilitate the removal of emboli from the blood, thereby reducing the possibility of complications. Medical practitioners have used occlusion devices, filters, lysing and aspiration techniques for removing embolic material. Treatment procedures employing occlusion balloon catheters and aspiration catheters have been developed to help prevent potentially embolic debris from migrating with the blood stream. The occlusion balloon catheter blocks or impedes blood flow while the aspiration catheter aspirates and removes embolic material from the area of the stenosis. Another common embolic containment procedure uses a wire-deployed emboli filter to trap emboli generated during treatment while permitting blood to flow through the filter.
Expandable embolic filters, which are conventionally fixed to the distal end of a guiding wire, have various configurations such as a mesh basket, a tube with multiple laser-drilled holes, a conical basket, a radially expandable mesh, or a structure with a distal coil wound about struts that form a hinge-type connection. Some filters are opened and closed in an umbrella-like fashion so that in the open position, the filter substantially fills the cross-section of the body lumen, whereas in the closed position, the filter with captured emboli is reduced in size to pass through the vessel lumen for removal.
Emboli filters as well as various other intravascular devices may be moved, opened, closed, or otherwise deployed with a wire. For example, a core wire moves slidable push-pull rods that open and close an embolic filter, as described in “Filter for Filtering Fluid in a Bodily Passageway,” Ladd, U.S. Pat. No. 6,059,814 issued May 9, 2000. The filter is expanded or contracted by pushing or pulling the core wire relative to the shaft of the hollow guidewire, thus controlling the relative axial positions of the filter ends.
Details of a filter or an occluder for capturing particulate in the vessels of a patient are found in Douk, et al., “Guidewire Apparatus for Temporary Distal Embolic Protection,” pending U.S. patent application Ser. No.10/099,399 filed Mar. 15, 2002, the contents of which are hereby incorporated by reference in their entirety.
One use of a friction-inducing wavy core wire in a valve mechanism for a balloon occlusion catheter is described in “Exchange Method for Emboli Containment,” Zadno-Azizi et al., U.S. Pat. No. 6,544,276 issued Apr. 8, 2003, the contents of which are hereby incorporated by reference in their entirety. The catheter includes a low-profile catheter valve with a movable sealer portion positioned within the inflation lumen of a catheter. The sealer portion forms a fluid tight seal with the inflation lumen by firmly contacting the entire circumference of a section of the inflation lumen. The sealer portion is positioned proximate to a side-access inflation port on the catheter, establishing an unrestricted fluid pathway between the inflation port and an inflatable balloon on the distal end of the catheter. The sealer portion can be moved to a position distal of the inflation port, thereby preventing fluid from being introduced into or withdrawn from the balloon via the inflation port. The wavy core wire induces a desired level of relatively constant friction to prevent the valve from inadvertently opening or closing.
With the aforementioned filter system and other medical catheter systems having core wires, it is important to control the movement of the devices that are moved, pushed and pulled axially by the core wire within a hollow guidewire or catheter. An improvement to such wire-controlled devices of catheter systems would provide greater control in the moving, positioning and locking of the devices. Preferably, differences in the frictional forces between the pushing and pulling of the wire could be distinguished by a medical practitioner, thereby increasing the performance of the medical devices used during the treatment of vascular conditions.